Background: Several surveys in the last 50 years have repeatedly indicated that Belgium is affected by mild iodine deficiency. Within the framework of the national food and health plan in Belgium, a selective, progressive, and monitored strategy was proposed in 2009 to optimize iodine intake. The objective of the present study was to perform a health economic evaluation of the consequences of inadequate iodine intake in Belgium, focusing on undisputed and measurable health outcomes such as thyroid nodular disease and its associated morbidity (hyperthyroidism). Methods: For the estimation of direct, indirect, medical, and nonmedical costs related to thyroid nodular diseases in Belgium, data from the Federal Public Service of Public Health, Food Chain Safety and Environment, the National Institute for Disease and Disability Insurance (RIZIV/INAMI), the Information Network about the prescription of reimbursable medicines (FARMANET), Intercontinental Marketing Services, and expert opinions were used. These costs translate into savings after implementation of the iodization program and are defined as costs due to thyroid nodular disease throughout the article. Costs related to the iodization program are referred to as program costs. Only figures dating from before the start of the intervention were exploited. Only adult and elderly people (>= 18 years) were taken into account in this study because thyroid nodular diseases predominantly affect this age group. Results: The yearly costs due to thyroid nodular diseases caused by mild iodine deficiency in the Belgian adult population are similar to(sic)38 million. It is expected that the iodization program will result in additional costs of similar to(sic)54,000 per year and decrease the prevalence of thyroid nodular diseases by 38% after a 4-5-year period. The net savings after establishment of the program are therefore estimated to be at least (sic)14 million a year. Conclusions: Optimization of iodine intake in Belgium should be quite cost effective, if only ...